1. Field of the Invention
The present invention relates to a technology for realizing various cooperative processes wherein various processors present on a network cooperate, and in particular to a security technology associated with cooperative processing.
2. Description of the Related Art
Workflow systems are currently being proposed in which various services can be provided for office functions by connecting to a LAN (Local Area Network) devices such as a scanner, a facsimile machine, a printer, a copier, and a multifunction device having these functions integrated so that these devices can communication with information processors such as personal computers or a mail server.
In recent years, technologies allowing various web applications to cooperate with one other have been proposed. It is highly expected that, if an overall system can be constructed by connecting various application services and service providers accessible through the Internet and provided, the cost for developing a system can be significantly reduced because existing services can be utilized. In connection with this, languages such as XML (eXtensible Markup Language) or the like also are attracting attention as a common platform enabling such cooperative services.
Examples of conventional workflow systems include those disclosed in, for example, Japanese Patent Laid-Open Publication Nos. Hei 8-123744, 2002-99686, and 2001-282970. An example of conventional art references that disclose an electronic signature is Japanese Patent Laid-Open Publication No. 2002-353960, which does not otherwise relate to a workflow as described above. Japanese Patent Laid-Open Publication No. 2002-353960 discloses a computer system for securely executing a program code which allows a multi-task execution of verification and decryption processes of a signature by electronically signing each of the smallest units of memory assignment of an encoded program code.
A service forming the “flow” (the flow of work processes or operations) can be requested from an associated processor by sending some form of instruction data to the processor. When there is a possibility that the instruction data maybe falsified or spoofed, there may be cases in which the security level required by the processor cannot be satisfied.
In order to prevent such falsification or the like of data, an electronic signature system of PKI (Public Key Infrastructure) is now commonly employed. However, in a cooperative service such as a workflow, a simple electronic signature technology may not be sufficient for a processor to determine whether or not received instruction data is identical to the instruction sent by the requestor of the cooperative service. Although a system in which a processor applies a specific process to the received instruction data and transmit the processed data to the next processor is theoretically possible such a system is problematic in that the electronic signature originally attached to the instruction data by the service requestor may be lost or damaged by some of the processes applied during the flow.